In military aircraft and several types of space vehicles, air crew escape is ensured by ejection seats. An ejection procedure generally follows the following course. A canopy or escape hatch is normally opened from the cockpit so as to clear an escape path. The pilots seat is ejected or catapulted from the aircraft or space vehicle. However, at the time of ejection it is extremely important for the upward direction to be established so that the self-contained propulsion system normally installed on the seat can orient the ejection seat in an upward direction. This is necessary to ensure clearance from the ejection seat from a normally descending disabled aircraft; and secondly for ensuring proper attitude of the ejection seat in preparation of parachute deployment.
Prior art escape systems can safely recover people from altitudes as low as 200 feet above ground level, even with the pilot ejected in an inverted position.
One prior art approach is reported in an article entitled "Escape Low and Hot" coauthored by Armand J. Aronne and James P. Murray, the article appearing in Mechanical Engineering, May 1983, pages 31-38. In this article a prior art system is described which uses passive radiation for transmitting a signal to a seat microprocessor which is programmed for roll-maneuvering. A pitch and roll sensing system provides rate information once the ejection seat is clear of the aircraft. A dual actuator control system positions the seat rocket so as to enable the seat to reorient itself into an upward trajectory. A drawback of the reported system as well as that of other prior art devices is the requirement that relatively large antennas be installed on the seat. Further, other problems become encountered which prevent the establishment of the upward direction with reliability.